Medical imaging X-ray apparatuses are often used in hospitals as an aid for obtaining information for making a diagnosis. With the X-ray apparatuses, a shadow image of inside the body is created with the aid of X-rays that penetrate the body, as a function of the characteristics of the tissue of a region of the body that is to be examined.
For a flexible use of the X-ray apparatuses and increased economic efficiency, some X-ray apparatuses are constructed as mobile apparatuses. Such mobile apparatus may be used in common (e.g., by various units and departments) by the apparatus being moved between the individual facilities to locations where a radiological examination is about to be carried out. To provide traction for such a mobile X-ray apparatus and to supply power to the imaging system of such a mobile X-ray apparatus, lead-acid batteries are used. However, lead-acid batteries have the disadvantage of heavy weight and of a long charging time (e.g., from 5 to 7 hours). In intensive operation of an X-ray apparatus (e.g., in an operating theater), long charging times are problematic.
When operating an X-ray apparatus, electric currents with high amperage are briefly required for the actual imaging in order to operate the X-ray source of the X-ray apparatus. Typical power consumptions of mobile X-ray sources are between 2 kW and 25 kW. The high currents required for the X-ray apparatus are not drawn from the normal single-phase household power supply. For this reason, X-ray apparatuses may include a condenser unit as a current storage facility. The condenser unit may provide short-term electrical energy that flows with sufficiently high power values to operate an X-ray source. However, such condenser units only have a very limited storage capacity and therefore constantly have to be charged again via the power network. The X-ray apparatus therefore has to be connected on site to an electrical energy supply by an electric cable. In confined areas of a hospital (e.g., as in operating theaters), such cable connections may be very obstructive or may even be a safety hazard.
For example, in the field of C-arm X-ray systems, completely autonomous apparatuses have not yet been used. C-arm X-ray systems are may be provided with electrical energy by a stationary power connection, and a condenser unit is used as buffer storage to power the X-ray source.
A C-arm X-ray apparatus with a condenser unit as an energy storage device for the X-ray source is described in Fehre, et al. “Energiespeichereinheit als schnell aufladbare Speicherbatterie für motorisch unterstützte Gerätebewegungen von mobile Röntgengeräten” [Energy storage unit as a quick-chargeable storage battery for motor-assisted movements of X-ray mobile apparatuses], IPAS Publication 2014J18453. Fehre, et al. disclose an autonomous C-arm X-ray apparatus with an energy storage device having a quick-chargeable high performance condenser unit to supply the drive and X-ray generation unit. Condensers only have a limited storage capacity, restricting the autonomous time of operation. Moreover, condensers are discharged via a discharge current that drops exponentially. When operated by electrical energy from the condensers, no constant operating current is supplied over time, necessitating a constant readjustment and complex power electronics.